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Scientists hunting for new antibiotics have scooped them from soil. They have searched in oceans and caves. And now, they are picking them out of your nose.

In a new paper published Wednesday in the journal Nature, German researchers report the discovery of a new antibiotic produced by a bacterium that lives inside the human nostril.

Experts say the paper is fascinating not just for the discovery of a potential new antibiotic — one that can kill a superbug called MRSA — but because it opens a potential new frontier in the desperate search for novel antibiotics: ourselves.

“Finding a new antibiotic is relatively rare. In the human microbiome, it’s super rare,” said Gerry Wright, an antibiotic resistance expert with McMaster University, who was not involved with the study. The human “microbiome” refers to the trillions of microbes that live on our skin and in our guts.

“It’s yet another great example of looking where people have rarely looked before — and finding something cool.”

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This paper is just the latest effort to stave off what public health officials are calling a “post-antibiotic era” — a time when bacteria are resistant to all available antibiotics and a scraped knee or run-of-the-mill infection can kill.

People are already dying from once-treatable infections and deaths caused by superbugs, “are expected to become more frequent causes of death than cancer in the coming decades,” according to the study.

This crisis has renewed efforts to find new antibiotics and scientists have become increasingly creative in their search, with a handful of promisingnew compounds recently unearthed.

A starting point for this latest study was the observation that the bacterium Staphylococcus aureus, a common cause of infection, can be found in the nostrils of roughly 30 per cent of people.

These people are not necessarily infected — just “colonized” — though this bug is an opportunistic pathogen, causing pneumonia or serious infections in people who are sick or immuno-compromised.

The researchers asked themselves: what’s going on in the noses of people who aren’t harbouring this pathogen? One difference, they found, is the presence of another bacterium called Staphylococcus lugdunensis, which produces an antibiotic they’ve named “lugdunin.”

Analyzing the nasal swabs of 187 hospital patients, the researchers found that 9 per cent had this protective bacterium in their noses — and out of this group, only 6 per cent were colonized with Staphylococcus aureus.

In patients who didn’t have the bug, however, 35 per cent were colonized with Staphylococcus aureus.

“We started the project just for basic understanding (but) it led us to some very unexpected and exciting findings,” said co-author Andreas Peschel, a bacteriologist with the University of Tubingen.

“It was totally unexpected to find a human-associated bacterium to produce an antibiotic. This is usually known from soil or environmental bacteria.”

That said, bacteria-killing compounds have been discovered in the human microbiome before. After all, this is an ecosystem where more than a thousand microbial species compete for space, deploying antibiotics to kill their rivals.

But Staphylococcus lugdunensis uses a complex machinery to produce its chemical weaponry — something more often seen in bacteria living in soil, where the vast majority of modern-day antibiotics have been found.

“(This machinery) gives bacteria access to building blocks that otherwise they can’t get access to,” Wright explained. “And these researchers have shown that you can actually find that in some members of the human microbiome.

“That’s kind of a cool thing to me. You want to know: How did that happen? Does it happen a lot? Is there other examples of this in various microbiomes, and not just human ones?”

Laboratory tests showed that lugdunin was effective at wiping out not just Staphylococcus aureus but also a superbug strain called MRSA, which is estimated to be 64 per cent more likely to cause death than non-resistant staph infections.

The antibiotic also cured mice infected in lab experiments.

“Some of the animals were completely cleared of Staphylococcus aureus,” said co-author Bernhard Krismer, a bacteriologist with the University of Tübingen in Germany. “No single cell of the bacterium was detectable.”

Other mice still had traces of infection but the researchers believe they licked off their antibiotic ointment.

The researchers don’t understand how, exactly, lugdunin is killing the bacteria and they say more work is needed to determine whether the antibiotic is safe or effective in humans.

They suggest that antibiotic-producing bacteria like Staphylococcus lugdunensis could someday be used as a probiotic, however, given to vulnerable patients to prevent staph infections.

They have also filed patent applications and hope to attract interest from drug companies. There are early signs that lugdunin might only be useful as a topical antibiotic — but even if everything goes well, it will take hundreds of millions of dollars, and several years before the antibiotic is ready for market.

Peschel believes lugdunin is just the first such example of this kind of antibiotic, with more probably waiting to be mined from the human microbiome.

The creativity and innovation of this work also gives Wright hope in the face of what many are calling a looming “antibiotic apocalypse.”

“Necessity is the mother of invention,” he said. “We’re entering into what I think is a new golden era of antibiotics, just because there’s a lot of really creative science happening.”

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